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Because Apple have custom ACPI methods for cutting power to unused components and Windows doesn't know how to call them.



That might explain the case of MacBook Air, but how come they don't do something similar with Surface Pro? It is their hardware, firmware and software - everything should be possible.


A quick Google search shows many Windows laptops with equivalent or better battery life. Is your question why don't all Windows laptops have equal battery life?


> A quick Google search shows many Windows laptops with equivalent or better battery life.

I don't want to state the obvious, but different laptops have different capacity batteries. Atwood was comparing the 11" MBA to the Surface Pro 2 as they have similar battery capacities (SP2: 42 Wh, MBA: 38 Wh), and - as Maakuth notes -- are both made by companies in control of both software and hardware. The fact that you can find laptops with higher capacity batteries that have longer battery life doesn't prove very much.


A 100% true test is when you have the same hardware. Running windows on MBA is defect because Apple writes iOS for their hardware. So if we have a magical power to run iOS on another hardware and run Windows on that same hardware, then the test is fair. But that doesn't need to as windows-based tablets hardware are not always as polish as apple's.


They have numbers for your 100% true test. That is where the final 50% difference comes from.

2013 MacBook Air 13"

Under OS X: 14hr 26 min

Under Win8: 7 hrs 40 min

Though I am not sure I would call that 100% fair. Apple wrote the firmware and drivers used by each OS, so it has a vested interest in getting something out there that works but not optimizing for the competition.


Your parent already said he did not consider running Windows on Apple hardware to be a fair test; he was calling for running both on <GENERIC PC>


Yeah, but what are you going to see in the real world? You are going to see OS X on Apple hardware and Windows on whatever random box the person had handy. Sounds pretty much like what they tested.


The test indicates something more important than Window's performance and that is monothilic designer like Apple can in fact make a great product if the designer chooses to. If Windows were to make their own laptop and invest the same amount of resource into bothe software and hardware, the comparison will be more interesting.

In essence, your average OEM does not do a great job. The capacitor, the transistors they use are probably way cheaper than what Apple have put into their MBA. That is expected because after all, your Dell computer is not going to cost $1499.


iOS? OS X runs on MBA not iOS.


Yes, of course, Windows can be comparable on similar capacities. Does this need to be stated? Go read the reviews of some Acer or Samsung laptops. Extrapolating the problems of the Surface 2 to all computers with the same OS doesn't make sense. Microsoft isn't experienced at making computers, shouldn't be a surprise that they are bad at it right now.


The article's point was that on closely comparable hardware doing nearly the same task, the operating system seems to make a significant difference in battery power. Maybe other Windows PC makers are more experienced in making efficient drivers and tuning the OS delivered on disk? In a couple of reviews I read, that isn't the case:

First Samsung laptop review I read, a NP900X3E-K01US with a 44 Wh battery:

...battery life is disappointing for such an expensive laptop... [1]

Second, a Dell XPS 12 review:

50WHr battery ... Wi-Fi browsing test ... seven hours and 58 minutes

[1] http://www.cnet.com/laptops/samsung-ativ-book-9/4505-3121_7-...

[2] http://arstechnica.com/gadgets/2013/10/review-xps-12s-haswel...


I'm puzzled, your comments seem to claim simultaneously that:

* There is not a battery life problem on Windows machines.

* The battery life problem on Windows machines is not surprising.


No, I didn't say #2, I said it's not surprising that the Surface Pro gets poor battery life. My comment about this whole controversy is that you cannot project 1 computer's battery problems to the operating system. My Windows does get poor battery life but we haven't seen any evidence of that. Clearly it can get good battery life as there are real-life computers running Windows that get great battery life.


Not necessarily. I'm just wondering why isn't Microsoft pulling some of the Apple tricks with Surface Pro if suspending some part of hardware really is responsible of OS X's better power economy. As others have pointed out in this discusion, some legacies of Windows architecture probably adds to its battery use.


How many windows laptops have you found that actually has the battery life they promise in marketing?


My EeePC is still doing quite well. Everything else I have ever bought has been a massive lie on the order of "* battery tested by doing nothing with the wireless and screen turned off."


The Surface Pro is MS' V1. It is going to take a while for them to become as savvy at hardware design as Apple is. Is there really any surprise that the newcomer isn't quite as good as the old guard?


I doubt very much that the commodity hardware in Apple laptops exposes any ACPI methods of which other operating systems are unaware.

They are the same components as widely used, just packaged differently ( as lspci from Linux on an Apple machine will show ). From memory the only Apple-branded components were the SD card readers and the keyboard.

And how would Intel / Nvidia / Broadcom / Samsung / LG / whomever be persuaded to keep it a secret?


You might doubt it, but it's entirely true. Apple aggressively cut power to unused devices and provide out of band mechanisms to generate wakeup notifications. Apple will entirely cut power to an SDHCI or Thunderbolt controller that's not in use. Windows won't.

There's nothing secret about this. Anyone who spends a while looking at the ACPI tables will see it. Recent versions of ACPI provide a standardised mechanism for doing this, but Apple have chosen to continue using their custom implementation.


Apple does use an extra microcontroller or small processor in MacBooks and other machines that controls fans and probably a large number of other power related things. They call it the SMC:

http://en.wikipedia.org/wiki/System_Management_Controller

So maybe not ACPI, but homebrew.


Everybody does that. This has not much to do with ACPI. ACPI is mainly a software thing (yes, you have some dedicated register support in some chips, but the baseline of those that are absolutely necessary is quite small and well supported by chip vendors)

ACPI has also proven to be an idea with a very bad execution: much of the tables are filled with bugs, and the spec has been written by complete psychopaths. IIRC sometimes it is better to skip entire sections and to use a custom written driver for each OS (like Intel did for some processors or chipsets for Linux I think)

Remember that ACPI has been created in part by MS, and that Bill himself wanted a conception that was easy for windows and hard for the other. I'm not sure this has been executed for the conception (even though the result is a mess), but MS absolutely managed to create an ecosystem where board vendors test only on Windows and ship if this kind of work, regardless of the amount of obvious bug present in their ACPI code.


Sony manage to get pretty amazing battery life from their new Vaio Pro 11 and 13 models. I am really tempted to get one as it does pretty much everything I want from a high powered laptop and the price is pretty good in my opinion.


Though they did that by adding an additional battery.


It seems quite close or even better when normalized per watt-hour, see http://anandtech.com/show/7417/sony-vaio-pro-13-exceptionall...


Interesting. Do you have any sources to share?




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